1. Field of the Invention
The present invention relates to a method of forming a wound core by helically winding a core element and an apparatus used for forming the same. The wound core is used, for example, as a stator of an AC generator for an automobile.
2. Description of the Prior Art
Heretofore, it has been known that a band steel sheet such as a silicon steel sheet which has slots in one side to form a core element can be wound in a helex by continuously engaging with the slots of the core element a plurality of equally spaced pins arranged in a circle and feeding the core element through an arcuate passage which has a width slightly smaller than the width of the core element, elongating the core element at the opposite side to the slots and compressing it in the axial direction.
However, the side of the core element opposite to the slots is elongated, making the core element to be thinner in the step of forming the sheet into an arcuate shape because the core element is compressed while it is passed through the arcuate passage. Accordingly, when the core element is wound a gap is formed at the outer peripheral part of the wound core and the wound core is deformed in the assembly whereby the wound wire is damaged.
Moreover, the side of the core element opposite to the slots is elongated making its thickness nonuniform. Accordingly, in winding the core element, the pitches of the slots are not uniform and the operation for adjusting the slot pitches with high accuracy has been very difficult.